Eric Garcetti, the incoming mayor of Los Angeles, should step in quickly once he takes office to restart negotiations over L.A./Ontario International Airport.

The city of Ontario filed a lawsuit in Riverside County Superior Court on Monday to dissolve its 46-year-old agreement allowing L.A. to run ONT. It’s unfortunately a necessary step, given the way negotiations have flopped up to this point, but the matter should not ultimately be decided in a courtroom. The public money that would be spent on lawyers if the suit were pursued to its conclusion could better be spent on other public services.

Garcetti, who appears open to ceding Ontario airport to local control — for a price — will be in position to push the restart button on talks between L.A. and Ontario when he takes office next month. It should be high on his to-do list.

Outgoing L.A. Mayor Antonio Villaraigosa talked a good game on regionalizing Southern California’s air traffic early in his tenure. But either it was just talk or he lost interest in the subject. And Gina Marie Lindsey, whom Villaraigosa appointed as executive director of Los Angeles World Airports in mid-2007, never has demonstrated commitment to spreading air traffic from LAX to ONT — in fact, quite the opposite.

ONT’s traffic has dropped from 7.2 million passengers in 2007 to 4.3 million in 2012, and it’s still dropping as other airports — including LAX — are showing healthy rebounds in passenger counts. Ontario officials estimate ONT will serve just 3.9 million passengers this year.

Ontario’s lawsuit seeks to end L.A.’s operating agreement on the grounds that LAWA has neglected and mismanaged the airport, thereby breaching its 1967 agreement to do its best to attract airline service to ONT.

The marketing campaign for ONT announced Tuesday by LAWA is an excellent step but comes awfully late in the game and, rather obviously, only in response to pressure applied by Ontario and the legion of other regional cities and governmental bodies that back local control for the airport.

Failure to market ONT is one of the ways that LAWA has breached its agreement, Ontario claims in its lawsuit. LAWA spent between $2 million and $3 million a year on marketing ONT from 2005 to 2007, compared to just $93,000 in fiscal year 2010, the lawsuit says. Meanwhile, LAWA spent $7 million for advertising and public relations to market LAX in fiscal year 2010.

Ontario Councilman Alan Wapner, who is also president of Ontario International Airport Authority, holds out hope that Garcetti will be much more accessible than his predecessor to Inland Empire leaders working on a potential airport transfer.

“My priority for Ontario airport is to increase regional capacity and increase passenger traffic there because that reduces the burden on LAX and its surrounding neighborhoods,” Garcetti said in April. That’s the right stance, true to the regionalization agreement that settled lawsuits brought against LAX by neighboring cities years ago.

This latest lawsuit could be settled too, if Garcetti demands good-faith negotiations to return ONT to local control.